Acta physiologica Scandinavica
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Acta Physiol. Scand. · Oct 2004
Evaluation of a triple sugar test of colonic permeability in humans.
Conventional dual sugar tests of intestinal permeability assess only the stomach and small intestine. A novel triple sugar method of assessing colonic permeability has recently been described in animals. This utilizes the non-fermented sweetener sucralose, in addition to conventional sugars. It has been postulated that this test enables the simultaneous assessment of small-intestinal and colonic barrier function in humans. The aim of this study was to evaluate the triple sugar test using healthy volunteers and ileostomists. ⋯ Both sucralose and 51Cr-EDTA underwent significant colonic absorption. A significant amount of lactulose also appeared to be absorbed in the colon. This unexpected finding requires further study.
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Acta Physiol. Scand. · Feb 1997
Heterogeneous blood flow response in the foot on dependency, assessed by laser Doppler perfusion imaging.
The exact nature of the decrease in foot skin blood flow seen after a change in posture remains unsettled. This mechanism has previously been examined by non-invasive techniques such as the laser Doppler perfusion monitor (laser Doppler flowmetry). Taking into account the shortcomings of laser Doppler perfusion monitoring when applied to the determination of skin blood flow, which normally shows substantial heterogeneity, we have applied an emerging technology, the laser Doppler perfusion imager (LDPI). ⋯ As the LDPI technique readily records skin perfusion during variations in venous stasis and posture, as well as information on flow distribution changes. It appears promising for future application in stimuli-response studies of skin blood flow. The difference in flow distribution seen between increased venous pressure and dependency suggests an additive regulatory mechanism to the veni-vasomotor reflex during a change in posture.
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Acta Physiol. Scand. · Dec 2003
Comparative StudyNon-invasive assessment of cardiac output during exercise in healthy young humans: comparison between Modelflow method and Doppler echocardiography method.
The Modelflow method can estimate cardiac output from arterial blood pressure waveforms using a three-element model of aortic input impedance (aortic characteristic impedance, arterial compliance, and systemic vascular resistance). We tested the reliability of a non-invasive cardiac output estimation during submaximal exercise using the Modelflow method from finger arterial pressure waveforms collected by Portapres in healthy young humans. ⋯ The Modelflow-estimated cardiac output correlated significantly with the simultaneous estimates by the Doppler method in all subjects (r = 0.87, P < 0.0001) and the SE of estimation was 1.93 L min-1. Correlation coefficients in each subject ranged from 0.91 to 0.98. Although the Modelflow method overestimated cardiac output, the errors between two estimates were not significantly different among the exercise levels. These results suggest that the Modelflow method using Portapres could provide a reliable estimation of the relative change in cardiac output non-invasively and continuously during submaximal exercise in healthy young humans, at least in terms of the relative changes in cardiac output.
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Acta Physiol. Scand. · Jan 1991
Effect of training on central factors in fatigue following two- and one-leg static exercise in man.
Leg strength and fatigue developed during 150 repeated two- and one-leg isometric maximal voluntary contractions were determined before and after a 5-week one- (n = 6) or two- (n = 7) leg training programme including a control group of five subjects. Two- and one-leg training increased two- and one-leg strength by 59 (range 8-107) and 36% (-1-69) respectively (P less than 0.01) with no significant difference between the two groups. Two-leg training decreased (P less than 0.05) fatigue only during two-leg maximal voluntary contractions (from 20 [11-26] to 13% [6-27]); and one-leg training fatigue only during one-leg maximal voluntary contractions (from 20 [15-23] to 11% [9-24]) despite the fact that both legs were trained. ⋯ No training effects were seen in the control group. The results show that an approximately 47% increase in muscle strength may take place without a significant change in the relative percentage of muscle fibre types or in the average muscle fibre size. Furthermore, the specificity of the training response to fatigue developed during repeated two- and one-leg maximal voluntary contractions suggests a change in the nervous influence on the motor units.
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Acta Physiol. Scand. · Jul 2002
Comparative StudyMechanisms of genioglossus responses to inspiratory resistive load in rabbits.
The purpose of the present study has been to determine whether pharyngeal dilator muscles participate in inspiratory load compensatory responses and if so, to elucidate role of upper airway mechanoreceptors in these responses. The experiments were performed on anaesthetized rabbits. Each animal was tested in three ways by the imposition of inspiratory resistive load: (1) at upper airways via face mask, (2) at the tracheostomic cannula placed below larynx (all upper airway receptors were 'bypassed') and (3) at the mouth after the section of the hypoglossus nerves (motor denervation of genioglossus muscle). ⋯ The results indicate that the pharyngeal dilator muscles have a role in compensation of added inspiratory load. Activation of these muscles facilitate the load compensating function of 'pump' muscles by decreasing airway resistance. Tracheostomy did not reduce the genioglossus response to inspiratory loading, ruling out any role for upper airways receptors in the genioglossus response to inspiratory load compensations.